Antispread device for industrial truck masts



ANTISPREAD DEVICE FOR INDUSTRIAL TRUCK MASTS Filed Nov. 14, 1960 T. G- KUSH Jan. 30, 1962 2 Sheets-Sheet l T. G. KUSH 3,018,849

ANTI-SPREAD DEVICE FOR INDUSTRIAL TRUCK MASTS Jan. 30, 1962 2 Sheets-Sheet 2 Filed Nov. 14, 1960 United States Patent 3,018,849 ANTISPREAD DEVICE FOR INDUSTRIAL TRUCK MASTS Theodore G. Kush, Park Forest, 111., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed Nov. 14, 1960, Ser. No. 68,935 4 Claims. (Cl. 187-9) This invention relates to an antispread device for preventing the lateral distortion of a pair of upright channels of an industrial truck mast.

Industrial lift trucks customarily have a pair of vertical channels in upstanding relation to the truck which support a load transporting carriage for vertical reciprocal movement. The carriage is customarily supported on the pair of channels through four rollers, two of which engage one channel and two of which engage the other channel. The upright channels are reinforced through bracing attached to their rear sides, however, the front sides of the channels are not braced since such bracing would interfere with operation of the forwardly projecting carriage which moves up and down in relation to the channels.

When the carriage is eccentrically loaded, that is, the center of mass of the load is to one side of the longitudinal central vertical plane of the lift truck, the load rollers which mount the carriage to the channels will bear against the channels and tend to spread them apart. Since the channels are secured at their rear sides through bracing, the channels will bend to laterally outwardly at their forward sides. In some instances this spreading or opening up of the channels is so serious that the load will pry the carriage out of the channels thereby presenting a very hazardous condition.

Heretofore, it has been suggested that a pair of rollers be placed on the bottom rear of the carriage to bear against the laterally outer surfaces of the channels and another pair of rollers be placed at the top rear of the carriage to bear against the laterally inner surfaces of the channels. With this arrangement the major portion of the eccentric loading is resisted by only one of the two channels. Although this prior art arrangement has been of some help in preventing distortion of the channel members, it has not been entirely satisfactory in that it does not equally distribute the extra loading caused by eccentric loading between the two channels. Also, prior arrangements have not allowed for adequate adjustment for Wear and manufacturing deviations. Further, the prior devices have been quite expensive to provide.

It is an object of this invention to provide an antispread device which takes care of the problems hereinbefore set out in an inexpensive and effective manner.

It is a further object of this invention to provide an antispread device for a pair of channels for a lift truck mast, whereby both channels resist the side thrust, imposed by eccentric loading of the carriage, to an equal degree.

It is a further object of this invention to provide an inexpensive traveling crosstie for resisting spreading of a pair of channel members for the lift truck mast which may be adjusted to compensate for manufacturing deviations and wear occurring in use.

These and other advantages and objects will be apparent upon the reading of the following description in conjunction with the drawings in which:

FIG. 1 is a side view of an industrial lift truck;

FIG. 2 is a front view of the truck shown in FIG. 1;

FIG. 3 is a section through the mast of the lift truck incorporating the present invention taken on line III-- III of FIG. 2;

FIG. 4 'is a partial section view taken on line IVIV in FIG. 3;

' 3,918,849 Patented Jan. 30, 1962 ice FIG. 5 is a schematic view of a mast in which the antispread mechanism of the subject case is employed;

FIG. 6 is a schematic view of a mast utilizing a prior art stabilizing arrangement;

FIG. 7 is a schematic view illustrating the eifect of eccentric loading without an antispread device; and

FIG. 8 is a section through the channels taken on line VIII-VIII of FIG. 7.

Referring to FIGS. 1 and 2, the lift truck 11 is equipped with a mast 12 which includes inner uprights 13 reciprocably mounted in outer uprights 14. The mast also includes a carriage 16 to which a pair of load supporting and transporting forks 17 are attached. The carriage 16 and the inner uprights are raised and lowered in a conventional manner by a lift ram 18 and a pair of chains 19. The outer uprights are braced at their upper ends by a pair of braces 21.

Referring to FIGS. 3 and 4, the outer uprights include a pair of vertically disposed channels 26, 27. Channel 26 includes flanges 28 and 29 connected by a web portion 31. Channel 27 includes a pair of flanges 33,34 which are connected by a web portion 36. The inner uprights likewise include a pair of channels 38, 39, the laterally outer sides of which carry trollers 41 for reciprocably supporting the inner uprights on the outer uprights.

Channel 38 has a web portion 42, at its laterally outer side, which is integral with flanges 43, 44. Likewise, channel 39 has a web portion 46 connected integrally by flanges 47, 48. The inner upright channels 38, 39 are connected at their rearward flanges 43 and 47 by upper and lower cross braces 51 and a transverse brace 50.

The carriage 16 has a pair of rearwardly projecting portions 52, 53 at its rear side. The laterally outer side of each of these portions 52, 53 carry a pair of combined roller assemblies, the four roller assemblies being designated 54, 55, 56, 57. The details of the carriage roller assemblies 54, 55, 56 and 57 are disclosed in Samuel T. Comfort Patent U.S. 2,881,031, issued April 7, 1959, Guide Rollers for Lift Truck Carriage. Guide roller assembly 54 includes an inner roller 59 within an outer roller 61. Likewise, inner rollers 62, 63, 64 are nested within outer rollers 66, 67 and 68, respectively. Side thrust rollers 59, 62 roll on inner surface 70 of web 42 and side thrust rollers 63, 64 roll on inner surface of web 46. Outer rollers 61, 66 bear against inner surfaces 79, of flanges 43 and 44, respectively, and outer rollers 67, 68 bear against inner surfaces 87, 88 of flanges 47, 48, respectively.

Heretofore when the center of gravity of a load being transported by the forks 17 of the carriage 16 was to one side of the longitudinal central vertical plane 60 of the lift truck, the carriage rollers would bear against the web portions 42, 46 of the channels 38, 39 and thereby deflect them as shown in FIG. 7. In some instances the eccentric loading is so extreme that the elastic limit of the channel metal is exceeded and the channels are deformed to the condition shown in FIG. 8. When this occurs, the

channels may be spread to such an extent that the carriage will actually be pried out of the channel members. This of course produces a hazardous condition forboth personnel and property.

The side thrust rollers 59, 62, 63, 64 are particularly advantageous for proper reciprocal movement of the carriage 16 on the inner uprights 13. However, when an eccentric load is carried by the carriage, the side thrust rollers 59, 62,63, 64 actually aggravate the spreading of the channels due to their frictionless application of side thrust load to the web portions of channels 38, 39.

In order to prevent the spreading of the channels 38, 39, I have provided a traveling crosstie in the form of a pair of guide rails 71, 72 which are fixedly secured to the 3 rear of the carriage in sliding engagement with the laterally outer sides of the channels 38, 39. Guide rail 71 includes a fixed portion 73 which is welded to the back of the carriage 16 and an adjustable portion 74 which may be spaced relative to fixed portion 73 through use of shims 76, The adjustable portion and shims are maintained in place by cap screws 77. The surface of the guide rail in contact with channel 38 may be of special wearing material such as bronze. As illustrated, a bronze wear strip 78 is attached to the adjustable portion 74 of the guide rail. Similarly, guide rail 72 includes a fixed portion 81 welded to the back of carriage 16 to which adjustable portion 82 is secured by cap screws 83. Shims 84 are interposed between portions 82 and 81 and a bronze wear strip 86 is fixed to outer portion 82 for sliding engagement with the laterally outer side of channel 39. As illustrated in FIG. 4, the guide rails are spaced from the laterally outer surfaces of the channels 38, 39 by a slight amount to provide a free running relationship with the channels 38, 39 when the load on the carriage is not eccentrically mounted. When the load is eccentrically mounted with relation to the longitudinal central vertical plane 60, that is when the center of mass of the load is olfset from the longitudinal central vertical plane 60 of the truck, the guide rails will bear against the channels 38, 39 as illustrated in FIG. 5. The arrow 91 indicates the direction in which the center of mass of the load is acting When the truck is subjected to eccentric loading, as shown schmatically in FIG. 5, the channels 38, 39 will both resist the eccentric loading equally. As illustrated, the guide rail 71 and guide rail 72 both act against their respective channels 38, 39 and thereby both channels aid in resisting lateral tilting of the load. The guide rails 71, 72 act as a traveling crosstie to strengthen the channels 38, 39 since the guide rails 11, 72 are a fixed distance from one another and this relationship cannot be varied except through removal or addition of shims 76, 84. Through application of the guide rails 71, 72 it has been found that the channels 38, 39 are not deflected to such an extent that the elastic limit is exceeded, and therefore are not deformed to the condition illustrated in FIG. 8.

As the load tends to tilt the carriage 16 laterally, as shown in FIG. 5, roller 63 will bear against the web of channel 39 and the roller '62 will bear against the web of channel 38. Rotation is resisted not only by rollers 62 and 63 but. also by guide rail 72, particularly at its lower end, and by guide rail 71, particularly at its upper end. Rotation or lateral tilting of the carriage is resisted by application of thrust to two vertically spaced portions of channel 38 and two vertically spaced portions of channel 39 Referring to FIG. 6 a prior art stabilizing device for a mast is schematically illustrated. The structure utilized consists of a pair of outer rollers 101, 102 rotatably secured to the lower rear of the carriage and a pair of inner rollers 103, 104 rotatably secured to the upper rear of the carriage. When this prior art mast is subjected to an eccentrically mounted load having an effective force component acting in the direction of arrow 106, the roller 104 acts against the laterally inner side of channel 108 while the roller 102 acts against the laterally outer side of the same channel. Rotation or lateral tilting of the carriage by the force 106 is resisted also by the sending action of roller 109 acting against channel 111. Thus it is seen that in this prior art arrangement lateral tilting of the load is resisted by the action of rollers 102, 104 on vertically spaced portions of the channel 108, however, channel 111 resists carriage tilting only by virtue of roller 109 bearing against the channel 111 at a single point. Thus it is evident that applicants antispread device for lift truck mast channels is considerably more effective in preventing distortion of the channel members through utilization of both channels to an equal extent in resisting lateral tilting of an ecoentrically mounted load.

The schematic showing of FIG. 7 illustrates the condition of the inner uprights, formed by channels 38, 39,.

when the antispread device in the form of guide rails 71,

72 are not utilized. When eccentric loading is applied to life.

Applicant has hereinbefore illustrated an extremely novel antispread device for industrial truck masts, in the form of a traveling crosstie formed by a pair of guide rails 71, 72 which are fixedly secured to the rear of a carriage 16 between upper guide roller assemblies 54, 56 and lower guide roller assemblies 55, 57. The guide rails are relatively inexpensive to provide, as compared particularly to the rollers of the prior art device of FIG. 6. Also, the adjustment of guide rails, permitted by addition or removal of shims 76 or 84, allows for slight manufacturing deviations and permits field adjustments to be made for wear occurring in use.

Although a single embodiment of the invention is illustrated, it is not intended to limit the invention except as necessitated by the scope of the appended claims.

What is claimed is:

1. In a lift truck mast the combination comprising: a pair of laterally spaced upright channels, a load transporting carriage supported for vertical reciprocating movement on said channels including a plurality of rollers rotatably secured to the rear of said carriage and having rolling contact with one of said channels and a plurality of rollers rotatably secured. to the rear of said carriage and having rolling contact with the other of. said chan-- nels, a first vertically extending guide rail fixedly secured to the rear of said carriage in sliding engagement with the laterally outer side of one of said channels and a second vertically extending guide rail fixedly secured to the rear of saidcarriage in sliding engagement with the laterally outer side of the other of said channels, said guide rails bearing against said channels, respectively, when said carriage is subjected to predetermined eccentric loading.

2. The structure set forth in claim 1 and further comprising means for adjusting said guide rails relative to said carriage.

3. In a lift truck mast the combination comprising: a pair of laterally spaced upright channels, a load transporting carriage supported for vertical reciprocating movement on said channels including a pair of vertically spaced rollers rotatably secured to the rear of said carriage and having rolling contact with one of said channels and a pair of vertically spaced rollers rotatably secured to the rear of said carriage and having rolling contact with the other of said channels, a first vertically extending guide rail fixedly secured to the rear of said carriage in sliding engagement with the laterally outer side of one of said channels opposite to the vertical space betwen said rollers and a second vertically extending guide rail fixedly secured to the rear of said carriage in sliding engagement with the laterally outer side of the other of said channels opposite to the vertical space between said rollers, said guide rails bearing against said channels, re spectively, when said carriage is subjected to predetermined eccentric loading.

4. The structure set forth in claim 3 wherein said channels have web portions disposed at their laterally outer side and said pairs of rollers rotate on longitudinal axes in thrust transmitting relation to the inner surface of said Webs, respectively.

References Cited in the file of this patent UNITED STATES PATENTS Such a mast is of no further utility' as its continued use would be dangerous to property and 

